1992 MAZDA PROTEGE ECU

SELF-DIAGNOSIS FUNCTION
Throttle sensor
Depress accelerator pedal (not fully) and check that
monitor lamp illuminates
YES NO
PC: *Throttle sensor malfunction CT page F-169
*Short circuit in wire harness
from throttle sensor to ECU
*ECU terminal 1 N (MTX) 1T
(ATX) voltage incorrect CT page F-150
l ECU malfunction
Depress acceleration pedal fully and check that monitor
No : PC: *Throttle sensor malfunction w page F-169
lamp does not illuminate *Open circuit in wire harness
from throttle sensor to ECU
YES *ECU terminal 2L (MTX) or 21
(ATX) voltage incorrect a page F-154
Throttle sensor OK
Release accelerator pedal
23UOFX-090
Stoplight switch
Depress brake pedal
Check that monitor lamp illuminates
YES
Stoplight switch OK
Release brake pedal NO
PC: *Stoplight switch malfunction w Section T
*Open circuit in wire harness
1
from stoplight switch to ECU
*ECU terminal 10 (MTX) 1Q
(ATX) voltage incorrect CT page F-l 52
l ECU malfunction
23UOFX-091
Blower switch
---
Turn blower switch to 2nd or higher position
Check that monitor lamp illuminates
YES
Blower switch OK NO
__L PC: *Blower switch malfunction
*Open circuit in wire harness
from blower switch to ECU
l ECU terminal 1 S (MTX) 1 P
(ATX) voltage incorrect
l ECU malfunction p Section T
w page F-152
23UOFX-092
F-l 08

.-
IDLE SPEED CONTROL (ISC) SYSTEM I-
IDLE SPEED CONTROL (ISC) SYSTEM
DESCRIPTION
BP SOHC
AIR VALVE THROTTLE SENSOR
CLUTCH SWITCT (MTX)


‘IS PRESS/URE SWITCH ‘x.

. , SIS CONNECTt
(TEN TERMINAL)
DISTRIBUTOR
INHIEITOR SWITCH (ATX)/
NEUTRAL SWITCH (MTX) 3R
To improve idle smoothness, the ISC system controls the intake air amount by regulating the bypass air amount
that passes through the throttle body. This system consists of the ISC valve, air valve, ECU and input devices.
F-115

FUEL PUMP CONNECTOR
/
REAR SEAT C
FUEL SYSTEM F
PRECAUTION
Fuel Pressure Release and Servicing Fuel System
Fuel in the fuel system remains under high pressure even when
the engine is not running.
a) Before disconnecting any fuel line, release the fuel pres-
sure from the fuel system to reduce the possibility of injury
or fire.
1. Start the engine.
2. Push the rear seat cushion buttons and remove the
cushion.
3. Disconnect the fuel pump connector.
4. After the engine stalls, turn off the ignition switch.
5. Reconnect the fuel pump connector and install the rear
seat cushion.
b) Use a rag as protection from fuel spray when disconnect-
ing the hoses.
Plug the hoses after removal.
c) When inspecting the fuel system, use a suitable fuel pres-
sure gauge.
Caution
l Install hose clamps to secure the fuel pressure
gauge to the fuel filter and the fuel main hose to pre-
vent fuel leakage.
9MUOF2-122 OBUOFX-126
DlAGNOS&O,NNECTOR
03UOFX-12.
-
DISCONNECT CONNECTOR
/ TO RELEASE FUEL PRESSURE
03UOFX-12;
Priming Fuel System
After releasing the fuel pressure for repairs or inspection, the
system must be primed to avoid excessive cranking when first
starting the engine. Follow the steps below.
1. Connect the diagnosis connector terminals
F/P and GND
with a jumper wire.
2. Turn the ignition switch
ON for approx. 10 sec. and check
for fuel leaks.
3. Turn the ignition switch OFF and remove the jumper wire.
SYSTEM OPERATION
Fuel Pressure Hold Inspection
Warning
l Before performing the following operation, release
the fuel pressure from the fuel system to reduce the
possibility of injury or fire. (Refer to above.)
F-121

FUEL SYSTEM F
DISCONNECT CONNECTOR
TO RELEASE FU5L PRESSURE
REAR SEAT C
23UOFX-11:
REPLACE
03UOFX-14s Replacement
Warning
l Before performing the following procedures, release
the fuel pressure from the fuel system to reduce the
possibility of injury or fire. (Refer to page F-121 .)
l When replacing the fuel system parts, keep sparks,
cigarettes, and open flames away from the fuel.
1. Push the rear seat cushion buttons and remove the cushion.
2. Remove the fuel pump cover.
3. Disconnect the fuel pump connector.
4. Disconnect the fuel hoses.
5. Remove the fuel pump and fuel tank gauge sender unit as-
sembly.
Caution
l Secure the fuel hoses tightly.
+ Use a new seal rubber.
6. Install in the reverse order of removal.
F-l 27

FUEL SYSTEM F
STA
OBUOFX- 15
03UOFX-15
DISCONNECT CONNECTOR
TO RELEASE FUfL PRESSURE
REAR SEAT C
23UOFX-11
INSTALL CLAMPS
CIRCUIT OPENING RELAY
Inspection
Voltage inspection
I, Check voltage between the following terminals and a ground
using a voltmeter.
Ve: Battery voltage
Resistance inspection
1, Check resistance between the terminals using an ohmmeter.
Terminal Resistance (Q)
STA-El 21-43
B-Fc 109-226
B-Fp 00
Replacement
1, Remove the passenger side wall.
2. Disconnect the relay connector.
3. Remove the relay from ECU bracket.
4. Install in the reverse order of removal.
PRESSURE REGULATOR
Inspection
Fuel line pressure
Warning
l Before performing the following operation, release
the fuel pressure from the fuel system to reduce the
possibility of injury or fire. (Refer to page F-121.)
1, Disconnect the negative battery terminal.
2. Connect a fuel pressure gauge between the fuel filter and
the fuel main hose. (Install clamps as shown.)
3. Connect the negative battery terminal.
4. Start the engine and run it at idle.
5. Measure the fuel line pressure.
Fuel line pressure:
206-255 kPa (2.1-2.6 kg/cm2, 30-37 psi)
6. Disconnect the vacuum hose from the pressure regulator
and measure the fuel line pressure.
Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm2, 36-46 psi)
F-l 29
03UOFX-157

231JOFX-1
FUEL SYSTEM F
INJECTOR
Inspection
Operation check
1. Warm up the engine and run it at idle.
2. Listen for operational sound of each injector with a screw-
driver or a sound scope.
3. If no sound is heard, measure injector resistance.
4. If the injector resistance is OK, check wiring to the injector
and the voltages of the ECU terminals MTX (2A, 2U and
2V) ATX (3A, 3U and 3V).
(Refer to page F-152.)
Injector resistance
1. Disconnect the injector harness.
2. Measure resistance of the injector with an ohmmeter.
Resistance: 12-l 6Q
3. If not as specified, replace the injector.
03UOFX-1
DISCONNECT CONNECTOR
TO RELEASE FU5L PRESSUR
REAR SEAT C
23UOFX-1
OBUOFX-
GRQMMET
INSULATOR
c5
OSUOFX-
Removal
Warning
l Before performing the following operation, release
the fuel pressure from the fuel system to reduce the
possibility of injury or fire. (Refer to page F-121 .)
l When removing the fuel system components, keep
sparks, cigarettes, and open flames away from the
fuel.
1. Disconnect the connectors from the injectors.
2. Remove the injector harness from the delivery pipe.
3. Remove the bolts from the intake manifold.
4. Remove the delivery pipe with the injectors and the pres-
sure regulator.
5. Remove the injectors, grommets, and insulators.
F-131

EVAPORATIVE EMISSION CONTROL SYSTEM t
EVAPORATIVE EMISSION CONTROL SYSTEM
DESCRIPTION
/ /
ENGINE ENGINE
CONTROL CONTROL - INPUT - INPUT
UNIT UNIT
- -
SOLENOID VALVE SOLENOID VALVE k k / /
CHECK VALVE CHECK VALVE
(TWO-WAY) (TWO-WAY)
CHARCOAL CHARCOAL
CANISTER CANISTER
CHECK-AND-CUTC CHECK-AND-CUTC
VALVE VALVE
SEPARATOR SEPARATOR TO ENGINE TO ENGINE SIGNALS
The evaporative emission control system consists of the separator, the check-and-cut valve, the two-way
check valve, the charcoal canister, the purge control solenoid valve, the engine control unit (ECU), and the
input devices. The amount of evaporative fumes introduced into the engine and burned is controlled by the
solenoid valve to correspond to the engine’s operating conditions. To maintain best engine performance,
the solenoid valve is controlled by the ECU.
Operation
.._ The solenoid valve (purge control) is controlled by duty signals from the ECU to perform purging of the char-
coal canister. Purging is done when these conditions are met:
(1) After warm-up
(2) Driving in gear
(3) Accelerator pedal depressed (idle switch OFF)
(4) Oxygen sensor functioning normally
F-l 39

FUEL CUT CONTROL SYSTEM F
FUEL CUT CONTROL SYSTEM
DESCRIPTION
This system is used to improve the fuel economy, to prevent engine bucking during deceleration, and to
protect the engine from overspeeding.
23UOFX-127
PREPARATION
SST
r
49 9200 162
03UOFX.191
l7=---T II USE CPNNECTOR A
03UOFX-19
SYSTEM OPERATION
1. Connect a tachometer to the diagnosis connector IG-
terminal.
2. Connect the
SSTs (Engine Signal Monitor and Adapt-
er)
to the engine control unit (ECU).
3. Warm-up the engine to normal operating temperature and
run it at idle.
Warning
l Confirm that transmission is in Neutral (MTX) or P
range (ATX).
4.
Set the SST (Sheet) on the Engine Signal Monitor with
the specified side fancing up as shown.
Note
l MTX...48 PIN
l ATX...64 PIN
I 23UOFX-128
F-l 43